DENVER — A Denver couple accused of keeping four malnourished young children in a filthy apartment pleaded guilty to neglecting three other children under strikingly similar conditions in 2006, court records show.

The parents, Wayne Sperling and Lorinda Bailey, appeared in court Tuesday on felony child-abuse charges. Authorities say their four boys, ages 2 to 6, lived in a rank-smelling apartment littered with cat feces, flies and urine. The boys could not speak and only grunted, authorities said.